1. Field of the Invention
The present invention relates to a host apparatus and a method for sensing failure in an external device connected through a communication cable. More particularly, the present invention relates to a host apparatus and a method for sensing failure in a power line and/or a data transmission line of an external device and informing a user of the failure.
2. Description of the Related Art
Recently, external devices such as Moving Picture Experts Group audio layer-3 (MP3) players and personal digital assistants (PDAs) have been produced without an internal power source. Instead, power is supplied from a host apparatus, such as a personal computer (PC), to allow for miniaturization and light weight. Likewise, as set-top boxes become miniaturized and light-weight, power may be supplied from a digital television (DTV) through a communication cable. The external device connected with the host apparatus through a communication cable such as a universal serial bus (USB) cable can be supplied with power from the host apparatus and perform data communication with the host apparatus.
FIG. 1 is a block diagram showing a conventional host apparatus for supplying power to an external device. The conventional host apparatus 10 comprises a power source 12, a power protector 14, and a communication port 16. The power source 12 receives an alternating current power of 110V or 220V from an alternating current power source 19 and converts the alternating current power into a power corresponding to the rated range of the host apparatus 10 and the external device 18. The power protector 14 shuts off the connection between the external device 18 and the power source 12, if the power source 12 provides a power beyond the rated range of the external device 18 to the external device 18. In other words, if the power line of the external device 18 is grounded or short-circuited with the data transmission line, an over current is supplied from the power source 12 to the external device 18. The power protector 14 such as a fuse shuts off the over current. Also, if the power is supplied abnormally to the external device 18 due to a problem in the power source 12, the power protector 14 shuts off the abnormal current. The communication port 16 is connected to the external device 18 through the communication cable.
In the above-described conventional method, if the external device 18 is connected to the host apparatus 10 and if the power supplied to the external device 18 is shut off to stop the operation of the external device 18, the user cannot determine whether the failure originates from the host apparatus 10 or from the external device 18.